1. Field of the Invention
This invention relates to an internal combustion engine including a valve deactivation mechanism.
2. Description of Background Art
An internal combustion engine including a valve deactivation mechanism is conventionally known wherein the valve deactivation mechanism is driven by hydraulic pressure to control an intake valve and an exhaust valve of the internal combustion engine. See, for example, Japanese Patent Laid-Open No. Hei 9-256879.
In addition, in an engine which uses a variable valve motion which uses hydraulic pressure, an oil control valve such as a spool valve is normally used in order to control the hydraulic pressure.
More particularly, in a cylinder deactivation engine including a valve deactivation mechanism, when the activation cylinder number is to be changed in response to an engine load, some interval of time is required after a driving instruction signal is outputted from an ECU to an oil control valve or the like until a hydraulic pressure necessary for the driving of a variable valve motion system is reached, and this provides a response delay.
If a cylinder deactivation/activation procedure does not take this response delay time into consideration, then an output power variation occurs when the activation cylinder number is changed, and there is a problem that an output power shock occurs.